add jems.gem so you can use it as is from jruby

gem/jems.gemspec

@@ -0,0 +1,14 @@
+#-*- mode: ruby -*-
+
+Gem::Specification.new do |s|
+  s.name = 'jems'
+  s.version = '0.1.5'
+  s.authors = ['Christian Meier']
+  s.summary = 'JRuby Jems'
+  s.files = ['jems.gemspec', 'lib/jems.rb']
+  s.platform = 'java'
+  s.requirements << "jar com.github.jrubygradle:jem, #{s.version}"
+  s.add_runtime_dependency 'jar-dependencies', '~> 0.1.15'
+end
+
+# vim: syntax=Ruby

gem/lib/jems.rb

@@ -0,0 +1,34 @@
+require 'jems_jars'
+module Jems
+
+  def self.jems_class_loader
+    @class_loader ||= com.github.jrubygradle.jem.JemsClassLoader.create
+  end
+
+  def self.activate( gem )
+    gemspec_raw = jems_class_loader.add_jem( gem )
+    gemspec = eval( gemspec_raw.to_ruby )
+
+    return false if Gem.loaded_specs[ gemspec.name ]
+
+    gem_name = 'gems/' + gemspec.full_name + '/.jrubydir'
+    url = jems_class_loader.get_resource( gem_name )
+    base = "uri:#{url.to_s.sub(/.jrubydir$/, '')}"
+
+    added = false
+    gemspec.require_paths.each do |path|
+      fullpath = File.join( base, path )
+      if File.directory?(fullpath) and not $LOAD_PATH.member?(fullpath)
+        # TODO rubygems insert before 'site_ruby' entry of the LOAD_PATH
+        $LOAD_PATH.unshift fullpath
+        added = true
+      end
+    end
+    # TODO check if gemspec.activate does the job better
+    if added
+      Gem.loaded_specs[ gemspec.name ] = gemspec
+    end
+    added
+  end
+
+end